IMS.Zmar. Expanses of clean or muddy fine sand in shallow water and on the lower shore
(typically to about 5 m depth) can have dense stands of Zostera marina/angustifolia
[Note: the taxonomic status of Z. angustifolia is currently under consideration but
is most likely a dwarf form of Zostera marina]. In IMS.Zmar the community
composition may be dominated by these Zostera species and therefore characterised
by the associated biota. Other biota present can be closely related to that of areas of
sediment not containing Zostera marina, for example, Laminaria saccharina, Chorda
filum and infaunal species such as Ensis spp. and Echinocardium cordatum
(e.g. Bamber 1993) and other bivalves listed below. It should be noted that sparse beds of
Zostera marina might be more readily characterised by their infaunal community.
Beds of this biotope in south-west Britain may contain conspicuous and distinctive
assemblages of Lusitanian fauna such as Laomedea angulata, Hippocampus spp.
and Stauromedusae. Some examples of Zostera marina beds have markedly anoxic
sediments associated with them.